A. Field of the Invention
This invention relates to a simple and inexpensive method for treating cataractous eyes by couching of the cataractous lens.
B. Background of the Invention
According to the Helen Keller Foundation, there are 28,000,000 people blind from cataract in the world and 17,000,000 blind from cataract in the third world. The numbers double every 20 to 25 years. For example, in India there are approximately 1,000,000 operations for cataract performed every year. Unfortunately, there are 1,500,000 new cataract candidates each year. In spite of the increased efforts of local ophthalmologists and various international organizations, the numbers continue to grow. Not only are there insufficient ophthalmic surgeons but also a lack of equipment. Most efforts entail intracapsular or extracapsular surgery with or without intraocular lens implants.
While intracapsular cataract extraction can be performed without the use of a surgical microscope, this instrument and careful follow-up are necessary for extracapsular surgery, particularly with an intraocular lens. There is also the problem of secondary opacification of the posterior capsule which usually requires the use of a Yag laser, another expensive piece of equipment, or surgical decision. These are all obstacles to a rapid restoration of sight for the majority of people blind from cataracts in the third world.
Couching, the original operation for cataract, performed first by the Hindu, Susruta, Circa 600 B.C., and later adopted by the Greeks, Egyptians and Romans, continued to be the operation of choice right into the 1750's. In couching, the instrument for couching was a curved, "barley-tipped" needle. This was a curved needle, the tip of which was shaped like a barley corn, tapering to a point and was made of brass. The needle was either inserted at the limbus into the anterior chamber and the lens pushed back into the vitreous or it was inserted through the pars plana and the lens dislocated inferiorly. If the lens was completely dislocated without rupturing the lens capsule, the lens would lie in the vitreous cavity in the inferior pole of the eye and the patients would see. Later, when spectacles were available their vision could be restored completely.
Unfortunately, couching often produced a rupture of the lens capsule and the patients would develop uveitis, glaucoma and other complications and 40%-50% would lose their sight.
In spite of the many complications that can occur with couching as a result of the rupture of the lens capsules, the practice continues on in various parts of the world, particularly in India and Nepal. Non-medical healers (couchers) go from village to village in the rural areas performing the technique. Although this practice is condemned by ophthalmologists, some reports are amazingly good. For example, Brandt, Hennig, Prasad, et al. (1984) examined 100 eyes which has undergone couching by "quacks", 1-10 years earlier. At the time of the examination, 42 eyes were found to be blind, most of which occurred immediately after the operation or within six months. The important point was that 68% of the eyes had vision preserved for the first year and subsequent loss of vision was less than 10% per year.
Belyaev and Barachkov two opthalmic surgeons, (1982) reported on 68 eyes which they couched and followed for 51/2 years. Vision of 20/20-20/40 was obtained 56/68 (82.4%). In 26 eyes without other pathology vision was 20/20. Eyes with other pathology such as corneal opacification, glaucoma, etc. had a mean visual acuity of 20/50. Mean for both groups was 20/30. There were three complications: one ruptured capsule requiring extraction and two vitreous prolapses into the anterior chamber producing glaucoma which required a vitrectomy.
C. Summary of the Invention
This invention involves the use of an enzyme to perform couching or dislocation of the cataractous lens. The procedure could be performed by a nurse or an ophthalmic assistant in a matter of minutes without the need of a surgical microscope or surgical instruments or prolonged post-operative care.
This invention is for a method of treating of cataracts in eyes by couching or dislocation of the cataractous lens. It includes the steps of introducing a zonulolysis-causing substance into the interior of the eye adjacent the cataractous lens in sufficient quantity and strength to produce zonulolysis of the lens zonules normally holding the lens of the eye in place. The zonulolysis-causing substance is maintained adjacent the lens zonules until zonulolysis occurs and said lens moves into the inferior cavity of the eye. Alphachymotrypsin is one form of zonulolysis-causing substance. That substance may be introduced through a clear portion of the cornea into the anterior chamber of the eye without rupturing the lens capsule. A quantity of aqueous may be removed from the anterior chamber before introducing the zonulolysis-causing substance therein. The substance may also be introduced by injection through the pars plana to a location behind the lens adjacent the lens zonules or by topical application of the substance in a carrier or together with iontophoresis which will cause the substance to move to the interior of the eye adjacent the lens zonules.